--- /dev/null
+.TP
+[\fB!\fP] \fB--mac-source\fP \fIaddress\fP
+Match source MAC address. It must be of the form XX:XX:XX:XX:XX:XX.
+Note that this only makes sense for packets coming from an Ethernet device
+and entering the
+.BR PREROUTING ,
+.B FORWARD
+or
+.B INPUT
+chains.